1. Field of the Invention
This invention relates to a radio frequency plasma display panel, and more particularly to a radio frequency plasma display panel that is capable of reducing a height of a barrier rib and a frequency of a radio frequency signal as well as improving a light-emission efficiency.
2. Description of the Related Art
Recently, a plasma display panel (PDP) feasible to the fabrication of large-scale panel has been available for a flat panel display device. The PDP takes advantages of a fact that an ultraviolet ray generated by a gas discharge radiates a fluorescent material to generate a visible light, thereby displaying a picture. There has been actively made a study as to a radio frequency PDP that is capable of dramatically improving a discharge efficiency and a brightness in comparison to the conventional alternating current (AC) surface discharge PDP. In the radio frequency PDP, electrons making an oscillating motion within a discharge space continuously ionize a discharge gas by a radio frequency of hundreds of MHz to make a continuous discharge for most discharge time. Such a radio frequency discharge has the same physical characteristic as a positive column at a glow discharge structure.
FIG. 1 is a section view showing the structure of a discharge cell in a conventional radio frequency PDP employing the above-mentioned radio frequency discharge. In FIG. 1, the discharge cell includes a radio frequency electrode 12 provided on an upper substrate 10, a data electrode 18 and a scanning electrode 22 provided on a lower substrate 16 in such a manner to be perpendicular to each other, and barrier ribs 28 provided between the upper substrate 10 and the lower substrate 16. The radio frequency electrode 12 applies a radio frequency signal. A first dielectric layer 14 is formed on the upper substrate 10 provided with the radio frequency electrodes 12. The data electrode 18 applies a data signal for causing an address discharge to select cells to be displayed. The scanning electrode 22 applies a scanning signal for said address discharge. Also, the scanning electrode 22 is opposed to the radio frequency electrode 12 in such a manner to be used as a counterpart electrode of the radio frequency electrode 12. Between the data electrodes 18 and the scanning electrodes 22 is provided a second dielectric layer 20 for charge accumulation and isolation. On the second dielectric layer 20 provided with the scanning electrodes 22, a third dielectric layer 24 for charge accumulation and a protective film 26 are sequentially disposed. The barrier ribs 28 shut off an optical interference between the cells. In this case, since a distance between the radio frequency electrode 12 and the scanning electrode 22 is sufficiently assured for the sake of a smooth radio frequency discharge, the barrier ribs 24 are provided at a higher level than those in the existent AC surface-discharge PDP. Alternately, the barrier ribs 28 may be formed into a lattice structure closed on every side for each discharge cell so as to isolate the discharge space. This is because it is difficult to isolate plasma for each cell unlike the existent surface discharge due to the opposite discharge generated between the radio frequency electrodes 12 and the scanning electrodes 22. A fluorescent material 30 is coated on the surface of the barrier rib 28 to emit a visible light with an inherent color by a vacuum ultraviolet ray generated during the radio frequency discharge. The discharge space defined by the upper substrate 10, the lower substrate 16 and the barrier ribs 28 is filled with a discharge gas.
The radio frequency PDP having the configuration as described above is driven with a drive waveform as shown in FIG. 2. A radio frequency signal RFS is continuously applied to the radio frequency electrode 12. When charged particles exist in the discharge space 32, a discharge is not generated even though the radio frequency signal RFS is applied to the radio frequency electrode 12. A data signal DS is applied to the data electrode 18 in an address interval AP and a scanning signal SS is applied to the scanning electrode 22, thereby generating an address discharge. Electrons having a relatively high mobility in the charged particles make an oscillation motion between the radio frequency electrode 12 and the scanning electrode 22 during a discharge-sustaining interval SP by virtue of the radio frequency signal RFS. The oscillating electrons excite a discharge gas to generate a vacuum ultraviolet ray, which radiates the fluorescent material 30 to generate a visible light. After such a radio frequency discharge was sustained in the discharge-sustaining interval SP, it is interrupted by an erasing signal ES applied to any one of the data electrode 18 and the scanning electrode 22 in an erasure interval EP. In other words, the oscillating electrons are drawn into an electrode coupled with the erasing signal ES to be extinct, thereby stopping the radio frequency discharge.
The conventional radio frequency PDP driven in accordance with such a discharge mechanism has several problems in view of it structure.
First, in order to sustain the radio frequency discharge smoothly, a distance between the radio frequency electrode 12 and the scanning electrode 22, that is, a height of the barrier rib must be sufficiently assured. This is because an oscillation width of the electrons making an oscillation motion within the discharge space 32 depends on a frequency of the radio frequency signal RFS. More specifically, as a frequency of the radio frequency signal RFS goes lower, an oscillation width of the electrons is more and more increased. For this reason, when a frequency of the radio frequency signal RFS is not sufficiently high or when a distance between the radio frequency electrode 12 and the scanning electrode 22 is not sufficiently assured, the electrons within the discharge space 32 collide with the upper and lower substrates to be extinct, thereby no longer sustaining a discharge. Accordingly, in order to improve discharge efficiency, it is necessary to raise a frequency of the radio frequency signal RFS or to sufficiently assure a distance between two electrodes 12 and 22 used for the radio frequency discharge. For instance, when a frequency of the radio frequency signal RFS is 200 MHz, an optimal discharge efficiency can not be obtain until a distance between the radio frequency electrode 12 and the scanning electrode 22 becomes about 2 mm. Herein, to raise a frequency of the radio frequency signal RFS requires a driving circuit and a driving method that is capable of treating a high frequency of radio frequency signal RFS. It is difficult to apply this scheme in view of the current technical state and the cost. Accordingly, it is necessary to sufficiently assure a distance between the radio frequency electrode 12 and the scanning electrode 22 so as to obtain desired discharge efficiency with lowering a frequency of the radio frequency signal RFS. However, since a scheme of assuring a distance between the radio frequency electrode 12 and the scanning electrode 20 is determined depending on a height of the barrier rib 28 shown in FIG. 1, it has a burden in that the barrier rib 28 must be provided to have a large height. This is because it is difficult to implement a barrier rib having a large height of more than 0.5 mm by the conventional barrier rib fabricating methods such as the screen printing method and the sand blast method, etc. Also, when a height of the barrier rib 28 is more than 1 mm, it is difficult to uniformly coating the fluorescent material 30 on the inner surface of the barrier rib 28 and a transmissivity of a visible light generated from the fluorescent material 30 is reduced.
Second, the conventional radio frequency PDP has a problem in that, since the scanning electrode 22 is commonly used for an address discharge and a radio frequency sustaining discharge, a driving method is complicated and an electrical interference between the two discharges occurs. Particularly, the radio frequency signal RFS applied to the discharge cell makes an affect to an alternating current voltage source applying the scanning signal SS via the scanning electrode 22, and therefore the address discharge is influenced by the radio frequency signal RFS. A low pass filter has been used among the scanning electrode 11, the data electrode 18 and the alternating current voltage source so as to prevent such an influence of the radio frequency signal RFS. However, this more complicates the driving circuit.
Third, a thickness of the second and third dielectric layers 20 and 24 on the data electrode 18 used for an address discharge is very large. Since a data voltage applied from the data electrode 18 to the discharge space drops due to the thick second and third dielectric layers 20 and 24, an address driving voltage must be raised. If the second dielectric layer 20 is set to a small thickness so as to reduce a voltage drop value cause by the thick second and third dielectric layers 20 and 24, then a parasitic capacitance between the data electrode 18 and the scanning electrode 22 rises to increase a leakage current. Therefore, it is difficult for the conventional radio frequency PDP to control a thickness of the second and third dielectric layers 20 and 24 so as to optimize an address discharge characteristic.
Accordingly, it is an object of the present invention to provide a radio frequency plasma display panel that is capable of reducing a height of a barrier rib and a frequency of a radio frequency signal as well as improving a sustaining-discharge efficiency.
A further object of the present invention is to provide a radio frequency plasma display panel that is capable of minimizing a mutual interference between an address discharge and a radio frequency sustaining discharge.
A yet further object of the present invention is to provide a radio frequency plasma display panel that can obtain an optimized address discharge characteristic.
In order to achieve these and other objects of the invention, a radio frequency plasma display panel according to the present invention having a plurality of discharge cells arranged in a matrix type, each of which includes first and second substrates; first and second address electrodes provided on at least one of the first and second substrates to generate an address discharge; barrier ribs provided between the first and second substrates to define a discharge space; and first and second radio frequency electrodes provided the respective barrier ribs opposed to each other to generate a radio frequency sustaining discharge.